The above-referenced parent patent application discloses a digital video recorder which has intelligent video information management capabilities.
In any digital video recording apparatus, the large quantity of data inherently present in streams of video signals tends to require difficult trade-offs to be made between the storage capacity to be provided by the apparatus and the image quality to be available upon reproduction of the recorded video signals. The trade-offs can be particularly critical when it is desired to provide random-access to the recorded video signal, as is the case in the intelligent video information management (IVIM) recorder disclosed in the parent patent application. In a preferred embodiment of the IVIM recorder, recording of video signal streams generated by up to 16 cameras, with random access playback, is provided on one or more hard disk drives. To achieve an adequate recording duration on the hard disk drives, a number of compression strategies were proposed in the parent patent application. Given that the IVIM recorder was intended principally for application in video surveillance security systems, it was considered that a standard recording format corresponding to 240 lines of vertical resolution would provide reproduced signal quality that was adequate for the intended application, while substantially increasing the effective recording capacity relative to the NTSC standard of about 480 horizontal scanning lines.
However, it would be desirable in the IVIM system to provide flexibility so that the user can determine, in selected cases, to trade off recording capacity in favor of improved vertical resolution in the recorded image signal.